Exposure counter



Sept. 19, 1944. c. H. HARRIS EXPOSURE COUNTER Filed Oct. 5, 1941 INVENTbR. C Zz'mfon Aarrz's Patent ed Sept. 19, 1944 nxrosuaa COUNTER Clinton E. Harris, Ann Arbor, Mich, minor to Argus, Incorporated, a corporation of Michi- I an Application October 3, 1941, Serial No. 413,514

v 3 Claims.

The present invention relates to photographic cameras, and more particularly to exposure counting mechanisms for perforated roll film cameras. One of the objects of the present invention is to provide a simple and efilcient mechanism for indicating the number of exposures in a perforated roll film camera. Another object is to provide a camera in which the film is releasably stopped when a fresh exposure area has been moved into position. A further object is to provide a rugged self-contained mechanism for measuring and counting the exposures in a roll film camera. These and other objects and advantages reside in certain novel features of construction, arrangement and combination of parts, as will hereinafter be more fully set forth and pointed out in the appended claims.

In the drawing:

Figure 1 is a top plan view of a camera embodying my invention with parts broken away to show internal structure.

Figure 2 is a section taken on line 2-2 of Figure 1.

Figure 3 is a section taken on line 3-3 of Figure 1.

Figure 4 is a fragmentary front elevation of the counter dial.

In the drawing I have illustrated my invention as applied to a specific camera, but it is to be understood that it is applicable to a wide variety of cameras. The details of construction of the camera illustrated form no part of the present invention but are described and claimed in my copending application, Serial No. 413,518 filed concurrently herewith, and entitled Photographic camera."

The camera illustrated consists of a body portion having a supply roll cavity l and a take-up roll cavity A film track l2 extends between the cavities l0 and II and has the usual exposure aperture l3. The camera cover l4 which is releasably attached to the body portion carries a pressure plate I5 which is pressed forward by a spring It to hold a film l1 fiat at the exposure aperture l3. The camera body has a cavity which is closed by a front wall l8. The usual focusing 23 and 21 rigidly fixed thereto. These sprocket wheels are spaced apart a distance equal to the objective mount indicated at i 9 may be carried by this front wall I8.

The film track I2 is provided with two slots 2|! and 2| adjacent the takeup cavity I Two horizontal supports 22 and 23 project inwardly from the front plate It toward the film track l2. A vertical shaft 24 is fixed in these supports adjacent the slots 20 and 2|. The sleeve 25 rotatably distance between the slots 20 and 2| and pro- Ject through the slots 20 and 2| into the path of the film l1.

The present counter mechanism is illustrated in connection with the perforated 35 mm. film and the sprockets 23 and 21 engage in the perforations 28 and 29 of the film.

At the bottom of the takeup cavity N, there is a seat 30 for receiving the lower end of the usual film reel or spool 3|. This seat is carried b the removable cover H. A spindle 32 is rotatably lournalled in a bearing 33 carried by the camera body and projects downwardly into the cavity directly above the seat 30. The end of this spindle is bifurcated as indicated at 34 to engage the usual winding balance of the reel 3|. A knob 35 outside of the camera may be manually rotated to wind the film I1 on the reel 3|. In moving to this takeup reel 3|, the sprocket holes 28 of the film l1 positively engage the sprockets 2G and 21 and rotate the sleeve 25. In order to stop the film when a fresh exposure area has been moved into alignment with the exposure aperture l3, a stud 36 is rigidly fixed in the sprocket 26.

A shaft 31 is vertically slidable in supports 22 and 38. The end of this shaft 31 below the support 22 is reduced in diameter as indicated at 39. A fiat detent 40 is rotatably mounted on this reduced portion 39 of the shaft 31 and projects toward the shaft 24 into the path of the stud 36. A coil spring 4| encircles the reduced portion 33 of the shaft 31, one end of this spring 4| engaging the support 38 and the other end engaging the detent 40. This spring 4| thus serves both to urge the detent 40 and shaft 31 upward toward the support 22 and to press the outer end of the detent 40 against the sleeve 25. A pin 42 extends transversely through the bottom of the shaft 31 beneath the support 38, and prevents withdrawal of the shaft 31. A button 43 is formed on the upper end of the shaft 31 and projects above the top of the camera. When this button is depressed, the detent 40 is moved downward parallel to the shafts 31 and 24 out of the path of the stud 36. The sprockets 26 and 21 are then free to rotate, and the film may be wound on the takeup roll 3|. As soon as this winding movement is started, the button 42 should be released so that the detent 43 again moves upward into the path of the stud 36 so that the sprockets :16 and 21 have stopped after one complete reVolumounted on the shaft 24 has two sprocket'wheels The sprockets 26 and 21 are made of such size mechanism indicated at 45.

that their circumference is slightly greater than the length of the exposure aperture It. When the entire roll of film has been exposed, the film I1 is rewound on the supply roll 44 by a winding When the film is moved in this direction. the stud 86 engages the side of the detent 40 and moves the detent out of the way against the tension of the spring 4|. Thus, the entire roll of film can be rewound on to the supply spool 44 without actuating the release button 43.

In order to indicate the movement of exposures which have been made, the sleeve 25 has a threaded portion 46 between the sprockets 26 and 21. A

spindle 41 is rotatablyjournalled in the support of the spindle 41 and engages the threaded portion 46 of the sleeve 25. An indicating dial 49 is attached to the spindle 41 by a shoulder screw 50, and a spring washer 5| between the dial 48 and spindle 41 frictionally holds the dial 49 in set position on the shaft 41.

The front wall l8 of the camera is preferably recessed as indicated at 52, and the dial 48 is located within this recess. Thus, the dial is protected from accidental displacement. Immediately surrounding the shoulder screw 50, the dial 49 has a raised knurled portion 53 by which the dial may be adjusted relative to the spindle 41. An index 54 on the front wall of the camera cooperates with the markings on the dial to indicate the number of exposures which have been made.

The number of teeth on the threaded portion 46 and the worm wheel 48 are such that one complete revolution of the sprockets 26 and 21 turn the dial through only a single division. In operation, the camera is loaded by threading the film over the guide I! and sprockets 26 and 21 on to the takeup roll 3|. The camera is'then closed and the dial 49 rotated relative to the shaft 41 until the zero mark on the dial is opposite the index 54 on the camera body. Each exposure thereafter will then move the dial through One division so that the number of exposures will be accurately indicated.

From the foregoing, it will be apparent that I am able to attain the objects of my invention and provide a simple, eiilcient and compact exposure counting mechanism for cameras. While I have shown my invention as applied to a particular type of camera, it will be readily apparent that this construction can be used in cameras of many types.

I claim:

1. In a camera having takeup and supply spool chambers, a sprocket adapted to be engaged and rotated by film passing between the spools, said sprocket comprising a rotatable shaft and a toothed wheel rigid with said shaft, a lateral projection on said wheel, a slidable control plunger parallel to said shaft, a detent bar rotatably carried by said plunger and axially shiftable therealong in one direction, a combined compression and torsion spring surrounding said plunger and connected to said detent bar, said spring axially urging said plunger and detent bar in the direction of said toothed wheel, and said spring angularly urging said detent bar toward said sprocket until the side of said detent bar bears against said shaft, with the free end of said detent bar in the path of rotation of said projection, said projection being operable to rock 2. In a camera, a body having a front wall and a top wall, a pair of vertically spaced supports projecting inwardly from said front wall, a vertical sprocket shaft journalled in said supports, a pair of sprockets rigidly carried by said I shaft and adapted to engage the perforations of a strip of film, a third support carried by said front wall interiorly of said camera, an exposure counter shaft journalled in said support sub- Y stantially at right angles to said sprocket shaft,

a counter dial mounted on said exposur counter shaft exteriorly of said front wall; a worm gear on said last-mentioned shaft meshing with a worm provided on said sprocket shaft'intermediate said sprockets; a fourth support projecting downwardly from said top wall, a plunger mounted for vertical reciprocation in said fourth support and an extension provided on said third support, a pawl freely pivoted on said plunger,

a combined torsion and compression spring.

mounted on said plunger and urging said pawl axially toward one of said supports and angularly into engagement with said sprocket shaft, said pawl having a free end disposed in the path of rotation of an abutment carried by said sprocket shaft and adapted to lock the latter against rotation in one direction and p rmit free rotation in the opposite direction, means on said plunger exteriorly of said top Wall for shifting it endwise, and means for causing said plunger to shift said pawl axially out of the path of said abutment when said plunger is shifted, to permit rotation of said sprocket in said one direction.

3. In a camera having a body providing a front wall and an objective lens assembly on said front wall, a shaft journalled normal to and projecting through said front wall, an exposure counter dial carried by said shaft exteriorly of said wall, and cooperating with indicia means on the latter to indicate the'number of exposures, a sprocket shaft mounted for rotation at right angles to said indicator shaft carrying a pair of spaced sprock-- ets adapted to coact with a strip of film, a. worm pawl is engaged with said sprocket shaft, said abutment to pivot said pawl out of the way when said sprocket shaft is rotated in film re-windlns direction, and a shoulder on said plunger operable to engage one side of said pawl and move it; axially against the expansive action of said spring into a position out of the path of rotation of said abutment, when said plunger is shifted endwise, to permit rotation of said sprocket shaft in film winding direction, the torsional force of said spring maintaining said pawl in engagement with said shaft while said pawl is CLINTON H. HARRIS.

5 being shifted axially. 

